1. Field of the Invention
The present invention relates to a display device comprising element (a light emitting element) which is a light emitting material formed between electrodes, and emits light upon flowing a current between electrodes, and in particular, relates to a sealing structure of a light emitting device.
2. Description of the Related Art
In recent years, development related to a flat panel display device using a light emitting element has been carried out actively. The light emitting element is formed by a material that emits light upon flowing a current between a pair of electrodes. Differing from a liquid crystal, the light emitting element emits light by itself without using a backlight, and is extremely thin in itself. Therefore, the light emitting element is very advantageous to form a flat panel display device.
The reliability problem is one of the factors in which the light emitting element has not been put to practical use although the light emitting element has such good advantages. The light emitting element using an organic material is easily deteriorated due to moisture (water) and has a drawback in which long-time reliability is difficultly obtained. The light emitting element deteriorated by water results in decrease in luminance or non-light emission. It has been thought that these defects might cause dark spots (black spots) or shrinkage (which is a deterioration in luminance caused from the end of a light emitting device) in a light emitting device. Therefore, various measures have been proposed to prevent such deteriorations (e.g., see patent documents 1 and 2).
[Patent document 1]: Japanese Patent Application Laid-Open No. Hei 9-148066
[Patent document 2]: Japanese Patent Application Laid-Open No. Hei 7-169567
However, the above measures have not overcome the above-mentioned problems and an adequate level of reliability has not been obtained. Accordingly, reliability improvement has been further expected.